It is common for marine crafts to use one or more valves to regulate the flow of seawater through various fluid systems within the crafts. One type of fluid system is an internal engine cooling system, wherein seawater from the exterior of the craft is pumped through the cooling system to cool the engine. A type of valve typically used in these systems is a ball valve, which includes a ball seated on seat rings within a valve body and operable (via rotation) to regulate the flow of seawater through the valve. A seacock is a type of ball valve that includes a flange for securing to the hull of the craft and is typically used in marine applications.
When using ball valves in marine applications, seawater penetrates the interior of the valve between a ball and a valve body when the valve is moved from an opened position to a closed position. This occurs because the cylindrical passage (i.e. bore) through the valve ball is filled with water when the valve is open. When the valve ball rotates 90° to the closed position, water that is present in the cylindrical passage is deposited in the space between the ball, seats, and valve body.
Additionally, when the seawater is allowed to remain in the space between the ball and the valve body, nuisance marine growth (i.e. biological and non-living fouling material) can accumulate on the outer surface of the ball, the inner surface of the valve body, and on seat rings. The buildup of the nuisance marine growth makes it more difficult to operate the valve between open and closed positions (i.e., to rotate the ball) and possibly degrades the seal formed by the seat rings between the ball and the valve body.
To prevent freezing in winter, typical marine ball valves include one or more drains and corresponding drain plugs, which can be periodically opened to drain the seawater from the space between the ball and the valve body. However, these drain plugs must be manually operated and sea craft owners are prone to forget to drain the valves, thus allowing seawater to remain inside the valve for extended periods of time and allowing the buildup of fouling material, thus compromising efficient valve operation. Furthermore, even when drained, some seawater may remain trapped between the ball and the valve body, so that nuisance marine growth may still develop in this area.